A catalytic converter for purifying exhaust gas that carries a catalyst is used to purify a problematic gas component, which impairs the human body when it is emitted in the air, such as HC (hydrocarbon), CO (carbon monoxide), and NOx (nitrogen compound).
Such a catalytic converter is used in purification of exhaust gas from an automobile and a motorbike. In order to purify exhaust gas from an internal combustion engine, a catalytic converter carrying a catalyst is disposed in an exhaust gas flow channel. The catalytic converter carrying a catalyst is similarly used in a methanol reformer that reforms hydrocarbon compounds such as methanol with steam to generate hydrogen-rich gas, a CO remover that reforms CO into CO2 to remove CO, and an H2 combustion device that burns H2 into H2O to remove H2.
Such a catalytic converter is configured so that a honeycomb core obtained by winding a flat metal foil and a corrugated metal foil is partially joined to an outer jacket covering the outer circumferential surface of the honeycomb core in the radial direction. The honeycomb core has a large number of exhaust gas flow channels extending in the axial direction. Exhaust gas can be purified by allowing the exhaust gas to flow through the inside of the exhaust gas flow channels from an end surface on an inlet side toward an end surface on an outlet side of the honeycomb core.
As such a catalytic converter, a catalytic converter including a honeycomb core having a flat metal foil and a corrugated metal foil that are alternately laminated, wherein a large number of exhaust gas flow channels for allowing exhaust gas to pass therethrough are formed and extend in an axial direction and an offset structure having different phases of adjacent wave parts between the front and rear in the axial direction is provided is known (for example, see Patent Literature 1). FIG. 11 is a cross-sectional view in a part of a conventional corrugated foil. One wave part 100 of adjacent wave parts in the axial direction is shown by a solid line, and another wave part 100′ is shown by a dotted line. With reference to FIG. 11, the wave part 100 includes a top surface 101, and a pair of side surfaces 102 extending from both ends of the top surface 101 in an obliquely downward direction. A lower end part is in contact with a flat foil 200, and a connection part between the top surface 101 and each of the side surfaces 102 is angular.
As viewed in an axial direction (normal direction of a sheet surface), a side surface 102′ of the wave part 100′ extends toward a region corresponding to the inside of the wave part 100. Thus, the corrugated foil has an offset structure. Due to use of the offset structure, the flow of exhaust gas is changed from laminar flow to turbulent flow, and an action of stirring exhaust gas is caused. Therefore, the purification performance for exhaust gas can be enhanced.